A. Helen Rasmussen, PhD, RD, senior research dietitian in the Metabolic Research Unit at the Jean Mayer USDA Human Nutrition Research Center on Aging, answers:
“Green vegetables (and especially dark leafy greens) are excellent sources of vitamin K, and the most common targets of restrictions for patients on blood thinners. According to the USDA FoodData Central database, one cup of raw spinach contains 145 micrograms (mcg) of vitamin K, and just half a cup of boiled collard greens contains 530 mcg. One prune contains less than six mcg, and a cup of prune juice contains just under nine micrograms.
“A couple of prunes would seem unlikely to represent a concern with regard to dietary vitamin K for those on blood thinners, but remember that portion and context are important: One cup of pitted prunes contains 104 mcg of vitamin K, and prunes eaten on the same day as other high vitamin K foods (like leafy greens) will add to the cumulative total intake. Patients are often on blood thinners because of cardiovascular problems, so a diet rich in heart-healthy foods like vegetables and fruits is important. Be sure to discuss diet with your cardiologist if you feel too restricted or have fears about the intake of any nutrient or food, and ask for a referral to a registered dietitian if you feel you need more help building a healthy dietary pattern that works with your medical conditions, your medications, and your personal preferences.”